Plural stage gas turbine



United States Patent f The invention relates to gas turbine plant comprising independently rotatable turbine rotors arranged in series flow and in alignment with one another in a common casing, the rst row of stator blades'of the downstream turbine being arranged immediately after the last row ofL rotor blades of the upstream turbine so as to avoid any losses due to a circuitous path of the gases from the ex-k f haust of the upstream turbine to the entry of the downstream turbine.

A typical example of such a gas turbine plant comprises a charging turbine driving the compressor for the combustion air of the plant, and an independently rotatable power turbine for the useful power output arranged in series ow arrangement, the charging turbine forming the high pressure or upstream stage, and the power turbine forming the low pressure or downstream stage.

According to the invention the rst row of stator blades of the downstream turbine is arranged over the rotor of the upstream turbine.

In order that the invention be better understoodv and readily carried into eifect, an embodiment thereof will now be described with reference to the accompanying drawing which is a diagrammatic axial section through part of a gas turbine embodying the invention.

The rotor 1 of the charging turbine and the rotor 2 of the power turbine are arranged co-axially but independently rotatable about their axes in a commonV casing 3. The combustion gases arriving from a convergent annular nozzle 4 are directed by the first row `of stator blades S onto the rst row of rotor blades 6 of the charging turbine, followed in the-.present embodiment by a second row of stator blades 7 and a second row of rotor blades 8.

A shoulder 1a of the rotor disc 1 of the charging turbine extends axially beyond the last row of rotor blades 8, and the rst row of stator blades 9 Vof the power turbine is arranged immediately adjacent the said last row of rotor blades 8, i. e. over the shoulder 1a of the charging turbine rotor.

This row of stator blades 9 is followed by the iirst row s 2,711,304 ce Y `Patented June-'21, 1955 stator blades tted into said casing, two mechanically independent separate shafts journaled in alignment with'y and axially spaced from each other Yfor rotation inde-` pendently of eachother in said casing, an Yupstream turbine rotor disc and a downstream turbine rotor disc each arranged on one of the said separate shafts andfin series ow with one another lin said casing the said upstream turbine rotor disc having a downstream rim extension,y

the first row of stator blades of the downstream turbine being reaction blading arranged immediately over the said rim extension of the rotor disc of theupstre'am tur'V bine, said turbine-rotor discs being axially spaced from each other.

' 2.Y A gas turbine comprising a high pressure charging turbine rotor` disc having a downstream rim`extension,`

a low pressure power turbine rotor disc arranged in series liow with the said high pressure turbine rotor` disc, a com mon turbine casing enclosing both the saidfturbine rotor discs, two mechanically independent separate shafts journalled in alignment with and axially spacedV from eachV other for rotationindependentlyof each other in said casing and each vcarrying one ofthe said turbine rotor f discs, rows of statorblades arranged in the said chasing, the first row of stator blades of the said lowy pressure turbine being reaction blading arranged immediatelyover the said vrimextension ofthe rotor vdisc of the said high 'Y pressure turbine, said` turbine rotor discs being vaxially spaced from each other. L

3. A gas turbine comprising a common casing, two` mechanically independent separate shafts Vjournaled in'` alignment `with and axially spaced from each otherl for fr rotation independently of each other in said; casing, rowsof stator blades fitted into said casing, a high pressure turbine rotor disc mounted on one of the said shafts, a, rim

arranged'on saidgrotor disc, rotor blades fitted to said rim,` an axial extension of said rim downstream'of the of rotor blades 10 of the power turbine and, in the present embodiment, by another row of stator blades 11 and another row of rotor blades 12.

The upstream thrust of purely axialcompressors, axial compressors having a radial final stage, and single sidedv invention, by making the first stator blades 9 of the power turbine a reaction blading and arrangingkthem over the shoulder 1a of the charging turbine disc 1, the pressure in the space 13 between charging turbine disc 1 and power turbine disc 2 is reduced by an amount equal to the pressure drop across the said stator blading 9. Thereby the pressure after the charging turbine is reduced which increases the downstream thrust of the charging turbine and reduces the resultant upstream thrust on the common thrust bearing of the compressor and its charging turbine. It also reduces the downstream thrust of the power turbine.

What I claim as my invention and desire to secure by Letters Patent is: Y

1. A gas turbine comprising a common casing, rows of `Vthe said reaction stator blades, said turbine rotor discs rotor blades thereof, a low pressure turbine rotor disc mounted 'on `the other-'one of the said shafts and arranged Vin series ow with the said high pressure turbinejrotor disc, the Yfrst'rowof statorbladesfor the said low pressure turbine rotor` disc being' reactionV bladingVV arranged immediately over the'saidaxial extension of the. high pressure turbine rotor disc, said turbine rotor discs being axially spaced -from each other.

4. Avgas turbine comprising a commonffcasing, twoy mechanically*independent separate shafts journaled in, alignment lwith and axially spaced vfrom Veach other for rotation independently of cach otherin the said casing rows of stator-bladestted into said casing,`a high pressure turbine rotor disc mounted on one of the said shafts, a rim 'arranged on said rotor disc, rotor blades fitted" to i said rim, an axial extension` of said rim downstream, of

vthe rotor blades thereof, a row of reaction` stator blades arranged immediately Vover thelsaid extension, kand a low pressure turbine rotor 'disc mounted on thel otherone of the said shafts and arranged in alignment with the said high pressure turbine rotor disc inoperative: relation Yto being axially Vspaced from each other.

.Y References. Cited in the le of this patent l u NITED STATESy PATENTS 1,398,124 Cake L Nov. 22, 1921 1,597,467 Hodgkinson`.. Aug. 24, 1926 2,312,995 Anxionnaz Mar. 2, 19,43 2,375,006 vLarrecq May 1, 1945 2,399,046 Larrecq 'Apr. 23, 1946 2,476,179 Cameron k July 12, 1949 2,476,218r `Prime s July 12, 1949 2,483,616 Bergstedt,` Oct. 4, 1949 2,505,660 Baumannl Apr. 25 1950 Y FOREIGN'PATENTS 586,553V 

